A microfabricated sensor, for example a microfabricated atomic clock or a microfabricated atomic magnetometer, has a sensor cell with a sensor cavity containing a sensor fluid such as cesium. A signal path extends into the sensor cell through a window which is part of the sensor cell. The sensor cell has overall dimensions less than 25 millimeters to provide a usable package size, so that the signal path is within a few millimeters of every point in the sensor cavity. During operation of the microfabricated sensor, the sensor cell is heated to convert at least some of the sensor fluid to a vapor phase with a desired vapor pressure. When the microfabricated sensor is turned off, the sensor fluid condenses. A portion of the sensor fluid condenses on the window, in the signal path. When the microfabricated sensor is subsequently turned on, the window remains partially obscured in the signal path due to residue from the condensed sensor fluid. Obscuration of the signal path disadvantageously degrades performance of the microfabricated sensor.